Expandable fusions devices, instruments, and methods thereof

ABSTRACT

Expandable fusion devices, systems, instruments, and methods thereof. The expandable fusion device is capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. The fusion device may include a body, a first endplate, and a second endplate. A drive screw may be rotated to move the first and second endplates outwardly and into an expanded configuration. Instruments may be provided to ensure the implant is inserted safely and as intended.

FIELD OF THE INVENTION

The present disclosure relates to surgical devices, and moreparticularly, to expandable fusion devices capable of being installedinside an intervertebral disc space and then expanded to maintain discspacing, restore spinal stability, and facilitate an intervertebralfusion. The present disclosure further relates to instruments forinstalling the same.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY OF THE INVENTION

In accordance with the application, devices, systems, methods, andinstruments are provided. In particular, an expandable fusion device isprovided, which is capable of being installed inside an intervertebraldisc space to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. The device may beinstalled in an open, semi-open, or minimally invasive surgicalprocedure. The expandable fusion device may be capable of being placedinto the disc space down an endoscopic tube, for example, and thenexpanded into the expanded configuration.

According to one embodiment, an implantable system includes anexpandable device having a first endplate and a second endplate, a bodypositioned between the first endplate and the second endplate, and adrive screw and a lock positioned within the body. Rotation of the drivescrew is configured to increase or decrease a distance between the firstendplate and the second endplate, and the lock is configured to stoprotation of the drive screw. The drive screw may have a head portion anda shaft. The head portion may have a plurality of protrusions defining aplurality of notches therebetween, an annular ring, and acircumferential groove between the plurality of protrusions and theannular ring. The lock may have a first ring and a second ring connectedto the first ring by a strut. In a locked position, the second ring maybe configured to rest in the circumferential groove of the head portion,the strut may be located in one of the notches, and the first ring ofthe lock may rest on a top face of the head portion of the drive screw.In an unlocked position, the second ring may be translated out of thegroove, and the strut may be translated out of the notch in order topermit the drive screw to be rotated by a driver instrument.

According to one embodiment, an inserter instrument includes an insertersleeve, a threaded shaft, and a driver. The inserter sleeve may includean inserter body with a guide shaft extending from a proximal end to adistal end, and a handle at the proximal end. The guide shaft mayinclude a tubular member defining a channel therethrough. A firstplurality of splines may be defined within the channel at the proximalend. The threaded shaft may be positionable through the channel of theinserter sleeve. The threaded shaft may include a cannulated connectorshaft and a slide including a second plurality of splines configured toengage with the first plurality of splines. The driver may bepositionable through the threaded shaft. The driver may include a shaftwith a linear cam configured to engage the slider of the threaded shaft.When the driver is positioned through the threaded shaft and the linearcam engages the slider, the slider linearly translates towards thedistal end, thereby causing the first and second plurality of splines tomate, and thereby locking an implant to the inserter instrument.

According to another embodiment, a system for installing an expandableimplant includes the expandable implant and an inserter instrument. Theexpandable implant may include a first endplate, a second endplate, abody positioned between the first endplate and the second endplate, anda drive screw positioned within the body. Rotation of the drive screwmay be configured to increase or decrease a distance between the firstendplate and the second endplate. The inserter instrument may include aninserter sleeve, a threaded shaft positionable through the insertersleeve, and a driver positionable through the threaded shaft. Theinserter sleeve may include a guide shaft defining a channeltherethrough, and a first plurality of splines defined within thechannel. The threaded shaft may include a slide having a secondplurality of splines configured to engage with the first plurality ofsplines. The driver may include a linear cam configured to engage theslider of the threaded shaft. When the driver is positioned through thethreaded shaft and the linear cam engages the slider, the sliderlinearly translates forward, thereby causing the first and secondplurality of splines to mate, and thereby locking the implant to theinserter instrument.

According to another embodiment, methods of installing the expandableimplant are provided. A disc space of a patient may be accessed andprepared. Opposed tabs at the distal end of the inserter sleeve mayengage corresponding recesses on the implant. The threaded shaft may bepositioned through the inserter sleeve and a threaded distal tip of thethreaded shaft may threadedly engage the implant. The implant may bepositioned within the disc space. A driver may be positioned through thethreaded shaft. The linear cam of the driver may slide forward theslider of the threaded shaft causing the first and second plurality ofsplines to mate and locking the implant to the inserter instrument. Thedriver tip engages a corresponding recess in the head of the drive screwof the implant. The driver rotates the drive screw of the implant,thereby expanding the implant to the proper disc height. The implant maynot be released until the driver is withdrawn from the threaded shaft,thereby disengaging the splines.

Also provided are kits including expandable fusion devices of varyingtypes and sizes, rods, fasteners or anchors, k-wires, insertion tools,and other components for performing the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of an expandable fusion device shown between twoadjacent vertebrae;

FIG. 2 shows a side view of an expandable fusion device according to oneembodiment in a contracted position;

FIG. 3 shows a side view of the expandable fusion device of FIG. 2expanded in lordosis;

FIG. 4 shows a side view of the expandable fusion device of FIG. 3expanded in height;

FIG. 5 is an exploded view of the expandable fusion device of FIGS. 2-4;

FIG. 6 shows a cross-sectional view of the expandable fusion device atthe contracted height;

FIG. 7 shows a side view of the expandable fusion device at thecontracted height;

FIG. 8 shows a back view of the expandable fusion device at thecontracted height;

FIG. 9 shows a perspective view of the expandable fusion device at thecontracted height;

FIG. 10 shows a cross-sectional view of the expandable fusion deviceexpanded in lordosis;

FIG. 11 shows a side view of the expandable fusion device expanded inlordosis;

FIG. 12 shows a back view of the expandable fusion device expanded inlordosis;

FIG. 13 shows a perspective view of the expandable fusion deviceexpanded in lordosis

FIG. 14 shows a cross-sectional view of the expandable fusion device atthe expanded height;

FIG. 15 show a side view of the expandable fusion device at the expandedheight;

FIG. 16 is a back view of the expandable fusion device at the expandedheight;

FIG. 17 is a perspective view of the expandable fusion device at theexpanded height;

FIG. 18 is an exploded view of the drive screw mechanism according toone embodiment;

FIG. 19 is a close-up exploded view of the drive screw and locking ringshown in FIG. 18;

FIG. 20 is a close-up assembled view of the drive screw and locking ringshown in FIG. 18;

FIG. 21 is a close-up side view of the retaining ring of FIG. 18;

FIG. 22 is a cross-sectional view of the housing viewing the top of thelock and drive screw assembly providing clearance for the lock totranslate;

FIG. 23 is a cross-sectional view of the housing and drive screwassembly showing restriction of rotation of the lock and the screw;

FIG. 24 is a cross-sectional view of the housing viewing the top of thelock and drive screw assembly showing the lock in an unlocked position;

FIG. 25 is a cross-sectional view of the housing and drive screwassembly showing the lock in an unlocked position;

FIG. 26 is a cross-sectional view of the housing viewing the top of thelock and drive screw assembly showing the lock in a locked position;

FIG. 27 is a cross-sectional view of the housing and drive screwassembly showing the lock in a locked position;

FIG. 28 is an exploded view of a drive screw assembly with a frictionring according to one embodiment;

FIG. 29 is a close-up cross-sectional view of the assembly with thefriction ring of FIG. 28;

FIG. 30 is a perspective view of an endplate of the expandable fusiondevice;

FIG. 31 shows an exploded view of an inserter instrument according toone embodiment;

FIG. 32 is a close-up perspective view of the inserter engaged with theexpandable fusion device;

FIG. 33 is a close-up side view of the inserter engaged with theexpandable fusion device;

FIG. 34 is a PLIF lateral view of the inserter engaged with theexpandable fusion device;

FIG. 35 is a TLIF lateral view of the inserter engaged with theexpandable fusion device;

FIG. 36 is a close-up perspective view of the spring tab on the guideshaft of the inserter and the threaded shaft engaged with the guideshaft;

FIG. 37 is a close-up perspective view of the threaded shaft threadedlyengaged with the expandable fusion device;

FIG. 38 is a close-up perspective view of the splines inside the guideshaft of the inserter sleeve with the splines of the threaded shaftdisengaged;

FIG. 39 is a close-up perspective view of the splines inside the guideshaft of the inserter sleeve with the splines of the threaded shaftengaged;

FIG. 40 is a close-up view of the splines inside the guide shaft of theinserter sleeve with the splines of the threaded shaft disengaged;

FIG. 41 is a top view of the mechanism that forces the spline slider toengage with the splines on the guide shaft;

FIG. 42 is a partial cross-sectional view with the driver engaging andthe splines disengaged;

FIG. 43 is a partial cross-sectional view with the driver fully engagedand the splines engaged;

FIG. 44 is a cross-sectional view with the button engaged, and thedriver cannot be removed until the button is pressed;

FIG. 45 is a cross-sectional view of the inserter engaged with theexpandable fusion device;

FIG. 46 is a view of the drive screw mechanism with the drivermismatched;

FIG. 47 is a view of the drive screw mechanism with the driver properlyseated;

FIG. 48 is a close-up side view of a torque limiting handle attached tothe inserter;

FIG. 49 is a cross-sectional view of the torque limiting handle of FIG.48;

FIG. 50 is a side view of a bone funnel according to one embodiment; and

FIG. 51 shows an assembled view of the bone funnel of FIG. 50 and theinserter of FIG. 31.

DETAILED DESCRIPTION OF THE INVENTION

The goal of spinal fusion surgery is fusion of the two vertebraeadjacent to the targeted disc level, often done through an interbodycage procedure. The endplates of the implant come into contact with thepatient's vertebral endplates to thereby promote fusion. Implantation ofintervertebral spacers from a posterior approach requires surgeons to beaware of nerve roots and other anatomy as they pass a spacer into thedisc space. The posterior margin is smaller than the anterior margin ofthe disc space so in order to insert a static spacer to fit the anteriorspace, a spacer larger than the posterior space may need to be insertedpotentially causing damage during insertion. An expandable spacerimplant is able to start out small so it can be passed through theposterior margin and then expanded to get endplate to endplate fit inthe anterior aspect of the disc space. Access to the disc space mayrequire some type of inserter instrumentation rigidly affixed to theimplant that can be detached from the implant when required.Accordingly, embodiments of the present application are generallydirected to devices, systems, instruments, and methods for installingand expanding the implant.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disc material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an expandable fusion device 10 is shown betweenadjacent vertebral bodies 2 and 3. The fusion device 10 engages theendplates 4 and 5 of the adjacent vertebral bodies 2 and 3 and, in theinstalled position, maintains normal intervertebral disc spacing andrestores spinal stability, thereby facilitating an intervertebralfusion. The expandable fusion device 10 can be manufactured from anumber of materials including titanium, stainless steel, titaniumalloys, non-titanium metallic alloys, polymeric materials, plastics,plastic composites, PEEK, ceramic, and elastic materials. In anembodiment, the expandable fusion device 10 can be configured to beplaced down an endoscopic tube and into the disc space between theadjacent vertebral bodies 2 and 3.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device. The termsimplant, fusion device, spacer, and expandable device may be usedinterchangeably herein.

Referring now to FIGS. 2-5, an embodiment of the fusion device 10 isshown. In an exemplary embodiment, the expandable fusion device 10comprises a first or lower endplate 20, a second or upper endplate 30, ahousing or body 40 positioned between the first endplate 20 and thesecond endplate 30, a nose 50, a drive screw 60, a friction ring orwasher 70, a locking ring or lock 80, and a retaining ring 90. Theendplates 20, 30 may have two main pairs of ramps that allow forexpansion: two back ramps that mate with the two ramps of the body 40,and two front ramps that mate with the ramps of the nose 50. The drivescrew 60 advantageously provides a threaded mechanism for expanding andcontracting the expandable fusion device 10. The drive screw 60 may bemated with washer 70 to reduce expansion force and/or add friction tothe drive screw 60 while being seated inside the body 40 and threadedinto the nose 50. The lock 80 may be used to eliminate rotation to thedrive screw 60 while the retaining ring 90 may retain the drive screw60, lock 80, and/or retaining ring 90 in the body 40. To expand theimplant 10, the drive screw 60 is rotated pulling the nose 50 towardsthe body 40 and causing the endplates 20, 30 to ride up the ramps of thebody 40 and nose 50. When this happens, the implant 10 first expands inlordosis (shown in FIG. 3) and then expands in height (shown in FIG. 4).The expandable device 10 may include the same or similar features to anyof the expandable devices described in U.S. Patent Publication No.2017/0354512, which is hereby incorporated by reference in its entiretyfor all purposes. In particular, fusion device 10 may include featuressimilar to expandable device 800 shown in U.S. Patent Publication No.2017/0354512.

The first endplate 20 comprises a lower endplate having a first end 22and a second end 24. The first endplate 20 comprises one or more rampsor ramped portions configured to engage with the body 40 and/or the nose50 of the assembled device 10. In one embodiment, the first end 22comprises a pair of first end ramped portions 26 a, 26 b. Each of theseramped portions 26 a, 26 b is configured to engage corresponding lowernose ramps 52 a, 52 b on the nose 50 to aid with expansion of theexpandable fusion device 10. The second end 24 comprises a pair ofsecond end ramped portions 28 a, 28 b. Each of these ramped portions 28a, 28 b is configured to engage corresponding rear lower ramps 48 a, 48b (shown in FIG. 18) on the body 40 to aid with expansion of theexpandable fusion device 10. The first endplate 20 may include a firstcentral ramp 27 a and a second central ramp 27 b positioned between thefirst end 22 and the second end 24 of the first endplate 20. Each of thecentral ramps 27 a, 27 b may be configured to engage corresponding frontlower ramps 46 a, 46 b of the body 40 to aid with expansion of theexpandable fusion device 10. The ramps of the first endplate 20 areformed along a perimeter that surrounds a central opening 29.

The second endplate 30 may be the same or similar to endplate 20 (e.g.,a mirror image). The second endplate 30 comprises an upper endplatehaving a first end 32 and a second end 34. The second endplate 30comprises one or more ramps or ramped portions configured to engage withthe body 40 and/or the nose 50 of the assembled device 10. The first end32 comprises a pair of first end ramped portions 36 a, 36 b. Each ofthese ramped portions 36 a, 36 b is configured to engage correspondingupper nose ramps 54 a, 54 b on the nose 50 to aid with expansion of theexpandable fusion device 10. The second end 34 comprises a pair ofsecond end ramped portions 38 a, 38 b. Each of these ramped portions 38a, 38 b is configured to engage corresponding rear upper ramps 48 a, 48b on the body 40 to aid with expansion of the expandable fusion device10. The endplate 30 may include a first central ramp 37 a and a secondcentral ramp 37 b positioned between the first end 32 and the second end34 of the first endplate 30. Each of the central ramps 37 a, 37 b may beconfigured to engage corresponding front upper ramps 46 a, 46 b of thebody 40 to aid with expansion of the expandable fusion device 10. Theramps of the second endplate 30 are formed along a perimeter thatsurrounds a central opening 39.

The housing or body 40 extends from a first end to a second end andcomprises a front through bore 42 and a rear through bore 44. The frontthrough bore 42 comprises an opening through which the threaded shaft 64of the drive screw 60 extends therethrough. The rear through bore 44comprises an opening through which the head 62 of the drive screw 60extends therethrough. The rear through bore 44 also receives the washer70, the retaining ring 80, and/or lock 90 therein. The retaining ring 90may be received in a recess of the head 62, which is then received inthe rear through bore 44. In some embodiments, the retaining ring 90comprises a c-shaped ring.

The drive screw 60 comprises a head portion 62 and a shaft portion 64.The head portion 62 comprises a recess or opening 61 for receiving aninstrument, such as a driver or expansion tool (e.g., driver 116). Theopening 61 may include a tri-wing configuration with three evenly spacedslots, but the opening 61 could also be slotted, Phillips, torx, hex,square, or of any other suitable configuration. The head portion 62 maycomprise a recess 76 for receiving the lock 80. The head portion 62 canbe received in the rear through bore 44 of the body 40. The shaftportion 64 comprises a threaded portion that extends through the nose50. The threaded portion mates with threads 56 within the nose 50.Rotation of the drive screw 60 thereby causes movement or translation ofthe nose 50.

In some embodiments, one or more tools (e.g., an expansion tool) canengage the head 62 of the drive screw 60. Rotation of the drive screw 60in a first direction translates and draws the nose 50 inwardly, therebycausing expansion between the first endplate 20 and the second endplate30. As the nose 50 is drawn inwardly, upper nose ramps 54 a, 54 b engagefirst end ramped portions 36 a, 36 b of the second endplate 30, whilerear upper ramps 48 a, 48 b of the body 40 engage second end rampedportions 38 a, 38 b of the second endplate 30. Likewise, lower noseramps 52 a, 52 b engage first end ramped portions 26 a, 26 b of thefirst endplate 20, while rear lower ramps engage second end rampedportions 28 a, 28 b of the first endplate 20. The engagement of theseramps causes outward expansion between the first endplate 20 and thesecond endplate 30. Rotation of the drive screw 60 in a second directionopposite to the first direction translates the nose 50 outwardly,thereby causing contraction between the first endplate 20 and the secondendplate 30.

The nose 50 comprises a through hole 58 through which the shaft portion64 of the drive screw 60 can extend. The through hole 58 of the nose 50comprises nose threads 56 that engage and mate with the threads of theshaft portion 64. As noted above, the nose 50 comprises one or moreupper nose ramps 54 a, 54 b, which are configured to mate and engagecorresponding ramps on the second endplate 30. In addition, the nose 50comprises one or more lower nose ramps 52 a, 52 b, which are configuredto mate and engage corresponding ramps on the first endplate 20.

FIGS. 2-4 are side views of the expandable fusion device 10 of FIG. 5 inthe process of expansion in accordance with some embodiments. In someembodiments, the expandable fusion device 10 is advantageously capableof expansion, and in particular, lordotic expansion. In someembodiments, the device 100 can begin in a contracted state, as shown inFIG. 2. Afterwards, by pulling the nose 50 via rotation of the drivescrew 60, the device 10 can expand and tip into lordosis, as shown inFIG. 3. Once the device 10 has achieved maximum lordosis, the device 10can continue to expand in height in a parallel fashion, whereby both theanterior and posterior aspects expand at the same rate, until theimplant 10 reaches a maximum expansion, as shown in FIG. 4. In otherwords, once the device 10 reaches a particular lordotic angle (as shownin FIG. 3), the device 10 will maintain the lordotic angle throughoutthe expansion range until maximum expansion has been achieved, as shownin FIG. 4.

Turning to FIGS. 6-9, the contracted position of the implant 10 isshown. The lordotic growth is driven by a difference in ramp angle d1,d2. As best seen in FIG. 6, a difference in ramp angle d1 is seenbetween the front endplate ramp 36 a, 36 b and the nose ramp 54 a, 54 b.A difference in ramp angle d2 is seen between the back endplate ramp 38a, 38 b and body ramp 48 a, 48 b. For example, the differences d1, d2may range from about 1-5□, or about 3□. Although shown for endplate 30it will be appreciated that the same or similar difference in rampangles d1, d2 may be provided for endplate 20 as well. As best seen inFIG. 7, in the contracted height, the difference in angle d1, d2 causesthe implant 10 to be in a lesser lordotic state L1. In other words, evenwhen fully contracted, the upper and lower endplates 20, 30 may providea mild lordotic height L1 of about 1-5□, or about 2□ for the implant 10.

Turning now to FIGS. 10-13, the implant 10 is expanded in lordosis. Oncethe implant 10 begins to expand, the nose 50 is pulled back causing theangle difference d3, d4 to go to zero as the front ramp 36 a, 36 b ofthe endplate 30 begins to mate with ramp 54 a, 54 b of the nose 50. Forexample, the difference in ramp angle d3 between the front endplate ramp36 a, 36 b and the nose ramp 54 a, 54 b is now zero, and the differencein ramp angle d4 between the back endplate ramp 38 a, 38 b and body ramp48 a, 48 b is also zero. As this happens, the back ramps 38 a, 38 b ofthe endplate 30 are forced to mate with the ramps 48 a, 48 b in the body40. Once the ramps are all at the same angle, the implant 10 is now inits lordotic expanded state L2. In other words, when expanded inlordosis, the upper and lower endplates 20, 30 may provide a lordoticangle L2 of about 1-10□, about 4-8□, or about 8□ for the implant 10.There has been no expansion in the back at this point, just the frontcausing the lordotic angle L2 seen in FIG. 11. The total lordosis iscontrolled by the difference in ramp angle d1, d2 in the contractedstate. For example, if the ramp angle difference is 3□ for each endplate20, 30, the total change of lordosis when expanded is 6□ (two endplates20, 30 at 3□ equals 6□ total change for the implant 10).

Turning now to FIGS. 14-17, the implant 10 is fully expanded in heightwith the lordosis L3. As the implant 10 continues to expand and thefront nose 50 is pulled back more, the implant 10 expands in a parallelfashion (anterior and posterior grow at the same rate) because the rampsare now at the same angle and are forced to consistently translate upthe ramp at that angle. For example, the difference in ramp angle d3between the front endplate ramp 36 a, 36 b and the nose ramp 54 a, 54 bis maintained at zero, and the difference in ramp angle d4 between theback endplate ramp 38 a, 38 b and body ramp 48 a, 48 b is alsomaintained at zero. This causes the implant 10 to maintain lordosis butgrow in overall height. In other words, when expanded in height, theupper and lower endplates 20, 30 may provide a lordotic angle L3 (e.g.,8□) equal to lordotic angle L2 (e.g., 8□), but with a greater overallheight of the implant 10. Height expansion stops when the nose 50bottoms out on the body 40.

In some embodiments, the device 10 can be used via different approaches.For example, in some embodiments, the device 10 can be a TLIF devicethat enters a disc space via a transforaminal approach, while in otherembodiments, the device 10 can be a PLIF device that enters a disc spacevia a posterior approach. In other embodiments, the device 10 can be anALIF device that enters via an anterior approach. One skilled in the artwill appreciate that the device 10 is not limited to any particularapproach.

Turning now to FIGS. 18-21, the drive screw assembly is provided in moredetail. In particular, the housing or body 40, drive screw 60, frictionring or washer 70, locking ring or lock 80, and retaining ring 90 of theimplant 10 are shown, but the endplates 20, 30 are omitted for clarity.The drive screw 60 comprises head portion 62 and shaft portion 64. Theshaft portion 64 may be partially or fully threaded along its length. Aclose-up view of the head portion 62 is shown in FIG. 19. The headportion 62 has a plurality of protrusions 66 separated by a plurality ofnotches 68 located radially around the tip of the head portion 62 with acircumferential groove 76 behind the notches 68. The protrusions 66 mayinclude a plurality of equidistantly spaced projections, therebycreating the plurality of equidistantly spaced notches 68. Theprotrusions 66 may include quadrilateral projections, such as square orrectangular protrusions, thereby forming generally quadrilateral notches68 therebetween. Although it is envisioned that any suitable number,type, and shape of protrusions 66 and notches 68 may be selected. Thecircumferential groove 76 may be positioned between the protrusions 66and an annular ring 78.

The friction ring or washer 70 may be an annular ring having an outersurface 72 configured to contact the body 40 and an inner surface 74configured to contact the drive screw 60, for example, below the annularring 78 of the drive screw 60. The friction ring or washer 70 may or maynot be included in the assembly. When present, the optional frictionring 70 may help to reduce expansion force and/or add friction to thedrive screw 60 while being seated inside the body 40 and the drive screw60 is threaded into the nose 50 of the device 10.

As best seen in FIG. 19, the locking ring or lock 80 may include a firstring 82 and a second ring 88 connected by a strut 86. The lock 80 may beshaped such that the top portion is a full ring 82 with a centralthrough hole 84 off center of the outer geometry. In other words, thethrough hole 84 is not aligned with the central longitudinal axis of thedrive screw 60. The ring 82 connects with the strut 86 to a lowerC-shaped spring ring 88. The strut 86 may have a thickness greater thanthe thickness of the first or second rings 82, 88. As best seen in inFIG. 20, the lock 80 is first inserted onto the screw head 62 such thatthe C-ring 88 rests in the circumferential groove 76 of the screw head62 and the strut 86 is located in one of the notches 68. The top ring 82of the lock 80 rests on a top face of the screw head 62. The offsetopening 84 is partially aligned with the opening 61 in the head portion62 of the screw 60.

As best seen in FIG. 21, the retaining ring 90 has a generally C-shapedbody and includes an outer surface 92 configured to contact the body 40and an inner surface 94. The retaining ring 90 may include a pluralityof outer radial notches 96 and/or a plurality of inner radial notches 98that allow the ring 90 to deflect without deforming. The outer and innerradial notches 96, 98 may include arcuate cutouts. The notches 96, 98may be equidistantly spaced around the outer and inner surfaces 92, 94,respectively. As shown, the depth of the inner notches 98 may be deeperthan the depth of the outer notches 96. The notches 96, 98 may alsoalternate with an inner notch 98 separating each pair of outer notches96. Although it is envisioned that the number, location, and depth ofthe notches 96, 98 may be selected to provide the desired amount ofdeflection. The retaining ring 90 may include a tab 99 to allow theretaining ring 90 to be removed if desired. The tab 99 may be elongatedto protrude outwardly past the outer surface 92 of the ring 90. Theretaining ring 99 may be placed in the housing 40 behind the drive screwassembly to prevent it from disassembling.

As best seen in FIGS. 22 and 23, the drive screw assembly is orientedand inserted into the housing 40. As shown in FIG. 22, the housing 40 isdesigned such that there may be a clearance 41 for the lock 80 totranslate in the housing 40. In other words, the housing 40 may have agap or recess dimensioned slightly larger than the outer surface of thelock 80 to allow for translation of the lock 80. As shown in FIG. 23,the housing 40 may be also dimensioned to restrict the lock 80 fromrotating within the housing 40. In other words, the housing 50 may havean opening or recess 43 dimensioned substantially the same as the outerdimension of the strut 86, such that the lock 80 is unable to rotate. Inthis way, when the lock strut 86 is located in one of the screw notches68, the screw 60 is unable to rotate relative to the housing 40 sincethe lock 80 cannot rotate about the screw 60 and the lock 80 cannotrotate within the housing 40.

With emphasis on FIGS. 24 and 25, an unlocked position for lock 80 inhousing 40 is shown. To unlock the assembly, a driver (e.g., driver 116)of the same internal shape of the screw opening 61 is inserted into thescrew 60. During insertion, the driver will pass through the offsetthrough hole 84 in the lock 80 and translate the lock 80 out of thegroove 76 in the screw 60. The strut 86 is translated out of the recess68 in the screw head 62 and is received in a recess in the housing 40.This allows the screw 60 to freely rotate with respect to the lock 80.Thus, the drive screw 60 is rotatable to thereby expand or contract theendplates 20, 30.

With emphasis on FIGS. 26 and 27, a locked position for lock 80 inhousing 40 is shown. Once the driver is removed, the C-ring section 88of the lock 80 will draw the lock 80 back into a locked position, withthe lock strut 86 engaged with one of the screw notches 68 and the ring88 positioned within the recess 76 of the head 62. In the lockedposition, the screw 60 is unable to rotate and the implant 10 cannot beexpanded or contracted.

Turning now to FIGS. 28 and 29, a drive screw assembly with a washer orfriction ring 70 is shown in greater detail. FIG. 28 provides anexploded view of the body or housing 40, the washer or friction ring 70,and the screw 60. As best seen in the cross-sectional view of FIG. 29,the washer or friction ring 70 is inserted over the shaft 64 of thescrew 60 with a tight fit and bottomed out under the screw head 62. Inother words, friction ring 70 is positioned on a smooth portion of theshaft 64 under the annular ring 78 and is dimensioned such that itcannot pass the annular ring 78. This assembly may be inserted into thehousing 40 in a location that radially compresses the friction ring 70.The housing 40 may utilize a lead in taper to slowly compress thefriction ring 70 so that the ring 70 remains intact and does not peel orbecome damaged. The friction ring 70 may act in two ways, for example.First, the compressed fit provides resistance to the rotating screw 60in the form of friction. Therefore, depending on the extent of thecompression different amounts of torque may be required to overcome thestatic friction. Second, the location of the ring 70 under the screwhead 62 allows the ring 70 to act as a thrust washer, reducing thelikelihood of galling between the metal screw and metal housing whenhigh torques are reached. The friction ring 70 may be made of a suitablematerial to impart the appropriate friction, such as a plastic,including any variation of PEEK (polyetheretherketone). The ring 70 maybe used independently or in conjunction with the other locking designs.

With emphasis on FIG. 30, a close-up view of endplate 20, 30 is shown.The endplates 20, 30 may include a plurality of teeth or other surfaceprotrusions configured to engage the adjacent vertebral bodies 2 and 3.The device 10 may also include a roughened and/or porous surfacetreatment as described in U.S. Publication No. 2017/0354512. Theendplates 20, 30 may utilize a 3D printed design which allows forcomplex geometry to be manufactured with minimal manufacturing time. The3D printing may also result in surface texturing that can betterfacilitate bony on growth. For example, any of the 3D printingtechniques or designs may be used as exemplified in U.S. Publication No.2019/0343652, which is incorporated by reference herein in its entiretyfor all purposes.

Turning now to FIG. 31, an inserter instrument 100 may be used to insertand/or expand the implant 10 in the disc space. The inserter 100 mayinclude an inserter sleeve 110, a threaded shaft 112, a drive handle114, and a driver 116. Each of the primary components serves to ensurethat the implant 10 is inserted safely and as intended.

The inserter sleeve 110 may include an inserter body 124 with a guideshaft 120 and a handle 126, a spring tab 122 positioned along theprimary axis of the guide shaft 120, and a dowel pin 128 connecting theguide shaft 120 and handle 126. The guide shaft 120 may include atubular member, hollow tube, or cannula defining a channel 125therethrough. The guide shaft 120 extends from a proximal end 130 to adistal end 132 along a central longitudinal axis L. The handle 126 maybe angled relative to the guide shaft 120, for example, at about 90°relative to the longitudinal axis L of the guide shaft 120.

As best seen in FIGS. 32 and 33, one or more tabs 136 may be located onthe distal tip 132 of the guide shaft 120. For example, two opposingfixed tabs 136 on the distal tip 132 of the guide shaft 120 may beconfigured to engage with one or more recesses 45 in the body 40 of theimplant 10. The tabs 136 may be sized and dimensioned to mate with thecorresponding recesses 45 of the body 40 of the implant 10. The tabs 136may help to maintain the implant orientation relative to the handle 126of the inserter 100. The tabs 136 on the distal tip 132 of the guideshaft 120 may be designed with a pointed or angled tip such that theimplant 10 is drawn to one orientation or an opposed 180° orientation.

With emphasis on FIGS. 34 and 35, the distal portion 132 of the insertersleeve 110 may also include one or more groove cuts 138 that allows fora reference to the location of the back of the implant 10 when beingviewed under fluoroscopy. The cut or cuts 138 may be made in such a waythat as the angle of insertion is changed, the reference point is stillvisible during fluoroscopy. For example, two opposed cuts 138 may beprovided as angled or swept cuts along edges of the guide shaft 120 asshown.

Turning now to FIG. 36, the guide shaft 120 of the inserter sleeve 110may include a spring tab 122. The spring tab 122 may be positioned alongthe primary axis of the guide shaft 120. The spring tab 122 may beconfigured to place spring pressure on a shallow groove 123 on thethreaded shaft 112. The spring pressure may be high enough that when thethreaded shaft 112 is not threaded into the implant 10, and the inserter100 is tipped upside-down, the threaded shaft 112 will not fall out ofthe inserter sleeve 110. Thus, the spring tab 122 retains the threadedshaft 112 within the inner channel 125 of the guide shaft 120.

A plurality of splines 140 may be positioned inside the guide shaft 120on the proximal side 130 of the inserter sleeve 110. In particular, theproximal end 130 of the guide shaft 120 may have an enlarged portionwith the plurality of splines 140 radially positioned about the innerchannel 125 of the guide shaft 120. The splines 140 may include aplurality of linear ridges or teeth separated by linear grooves. Thesplines 140 inside the guide shaft 120 on the proximal side 130 of theinserter sleeve 110 are intended to engage with mating splines 150 onthe threaded shaft 112. As shown, the splines 140, 150 may includeparallel key splines. It is envisioned, however, that other suitablesplines may be selected, such as involute splines, crowned splines,serrations, helical splines, or the like.

The threaded shaft 112 is positionable within the channel 125 of theguide shaft 120 of the inserter sleeve 110. When the threaded shaft 112and inserter sleeve 110 are engaged (e.g., the splines 140, 150intermesh), the threaded shaft 112 cannot be rotated and therefore theimplant 10 cannot be removed until the splines 140, 150 are disengaged.The engagement of the splines 140, 150 is dependent on whether thedriver 116 is connected to the inserter 100 or not as explained in moredetail below with reference to the driver 116.

The threaded shaft 112 includes a cannulated connector shaft 158including an externally threaded portion 166 at its distal tip 162, aspring-loaded button 170 for releasing the driver 116, a spline slideror slider 148 including splines 150, a ring washer, a retaining ring174, a slider spring 176, and dowel pins 178. The threaded shaft 112 mayinclude a tubular member, hollow tube, or cannula defining a channel 165therethrough. The threaded shaft 112 extends from a proximal end 160 toa distal end 162 along the central longitudinal axis L.

As best seen in FIG. 37, the threaded portion 166 at the distal tip 162of the threaded shaft 112 includes external threads 166 that directlyengage with corresponding threads (e.g., within through bore 44) on theposterior wall of the implant 10. As the threaded portion 166 of thethreaded shaft 112 is threaded into the implant 10 (through the guideshaft 120) the implant 10 is drawn into the guide shaft 120 until theorientation tabs 136 align to the implant 10, and then the front of theguide shaft 120 bottoms out on the posterior wall of the implant 10.These threads 166 serve to keep the implant 10 drawn into the inserter100, and to keep the tabs 136 on the guide shaft 120 engaged with theimplant 10. Unlike a splaying fork style inserter prone to having theimplant pulled off, the fixed forks 136 and threaded connection 166 mayhelp to ensure that the implant 10 will stay oriented relative to thehandle 126 of the inserter sleeve 110, while also ensure that theimplant 10 stays secure to the inserter sleeve 110.

Further to FIGS. 38 and 39, the splines 140, 150 are shown in moredetail. Often inserters can become disengaged at unexpected andunintended times. The spline engagement features 140, 150 may help toensure that the implant 10 cannot be disconnected until the driver 116is removed. As best seen in FIG. 38, the splines 140 of the guide shaft120 are disengaged from the splines 150 of the threaded shaft 112. Inother words, the splines 140, 150 do not intermesh with one another.When the threaded shaft 112 is threaded onto the implant 10 (e.g., viathreads 166), the splines 150 on the spline slider 148 are not engagedinto the opposing splines 140 of guide shaft 120 (shown in FIG. 38). Inthis configuration, the threaded shaft 112 could still be turned (e.g.,counterclockwise) and removed from the implant 10.

As shown in FIG. 39, the splines 150 on the slider 148 of the threadedshaft 112 engage with the splines 140 on the inside of the guide shaft120. In other words, the splines 140, 150 are meshed with one another.As the driver 116 is placed through the threaded shaft 112, the driver116 pushes on the inside of the threaded shaft 112, thereby forcing thespline slider 148 to engage splines 150 with the splines 140 on theguide shaft 120. In particular, the linear cam 184 of the driver 116 maypush on engagement members 164 of the threaded shaft 112, therebylinearly translating the spline slider 148 forward and into the engagedpositioned shown in FIG. 39. Thus, the slider 148 is configured to slidelinearly along the longitudinal axis L towards the distal end 132 of theguide shaft 120, thereby causing the splines 140, 150 to mate (FIG. 39).The slider 148 is also able to slide linearly in the opposite directionalong the longitudinal axis L away from the distal end 132 of the guideshaft 120, thereby causing the splines 140, 150 to separate and becomedisengaged (FIG. 38).

As the driver 116 is advanced and the splines 140, 150 engage,eventually the driver 116 comes into contact with an engagement surfaceon the button 170 of the threaded shaft 112. The button 170 isspring-loaded such that once the driver 116 is placed far enough, thebutton 170 engages, and the driver 116 cannot be removed until thebutton 170 is pressed. Thus, the button 170 retains the driver 116,thereby ensuring that the driver 116 cannot be removed until activelydecided by the operator.

With emphasis on FIGS. 44 and 45, the driver 116 includes a driver base186, a driver shaft 188, a driver shaft spring 190, a dowel pin 192, anda handle retaining saddle 187 on the proximal end 180 of the driver 116.The driver 116 extends from a proximal end 180 to a distal end 182 alongthe central longitudinal axis L. The driver shaft 188 is configured tobe received through the channel 165 of the threaded shaft 112. Thedistal end 182 of the driver 116 includes a driving tip configured toengage the recess 61 in the screw head 62 of the implant 10.

As best seen in FIGS. 42-44, the driver shaft 188 includes a linear cam184 configured to engage the slider 148 of the threaded shaft 112. Thelinear cam 184 may be engaged with an engagement member 164 of thethreaded shaft 112, thereby linearly translating the slider 148 toengage the splines 140, 150 as described in more detail herein. Thelinear cam 184 may include one or more protruding cam surfaces, such asangled surfaces configured to mate with corresponding surfaces on theengagement member 164 of the slider 148. As the driver 116 is placedthrough the channel 165 of the threaded shaft 112, the linear cam 184 ofthe driver 116 may push on engagement members 164 of the slider 148,thereby linearly translating the slider 148 forward and causing thesplines 140, 150 to mate.

The driver shaft 188 may also define an annular groove 185 around theperimeter of the shaft 188 configured to receive the button 170 of thethreaded shaft 112. In order to remove the driver 116 from the assembly,the button 170 must be depressed. Then, as the driver 116 is withdrawnthe spline slider 148 slides linearly away from the distal end 132 ofthe guide shaft 120, thereby causing the splines 140, 150 to separateand become disengaged.

As best seen in FIGS. 46 and 47, the driver 116 allows for engagementinto the drive screw 60 regardless of orientation. FIG. 46 depicts thedriver 116 mismatched with the opening 61 of the drive screw 60. Inparticular, the tri-wing tip at the distal end 182 of the driver shaft188 of the driver 116 is offset relative to the tri-wing recess 61 inthe screw head 62 of the implant 10. Thus, the driver 116 is notproperly seated in the drive screw 60. FIG. 47 depicts the driver 116properly seated in the drive screw 60 of the implant 10. The tri-wingtip of the driver 116 is aligned with the tri-wing recess 61 of thescrew head 62 of the implant 10. Thus, the driver 116 is properly seatedin the drive screw 60. The engagement spring 190 in the proximal end 180of the driver 116 allows for engagement into the drive screw 60regardless of orientation. If the driver 116 is mismatched to the drivescrew 60 as the splines 140, 150 in the back of the inserter 110 engage,the engagement spring 190 allows for the driver 116 to push backwards sothat the splines 140, 150 can still engage. Once the driver 116 isrotated, the spring force from the engagement spring 190 will force thedriver 116 to seat within the drive screw 60.

The overall length of the driver 116 may vary in accordance with thesize of the implant 10 that is to be implanted. As the driver 116 ispushed through the threaded shaft 112, eventually the distal tip 182will come into contact with the drive screw 60 within the implant 10.The location of the drive screw 60 varies relative to the back of theimplant 10 with respect to length of the implant 10. The longer theimplant 10, the longer the distance from the back of the implant 10 tothe drive screw 60. Different length drivers 116 allow for the use ofthe same inserter 110, while still accommodating different lengthimplants 10.

With emphasis on FIGS. 48 and 49, the drive handle 114 is shown. Thedrive handle 114 may have an attachment member 194 configured to matewith the handle retaining saddle 187 of the driver 116 and a grip member196 configured to be rotated manually by hand. The drive handle 114 maybe configured as a torque limiting handle 114. The handle retainingsaddle 187 on the proximal end 180 of the driver 116 allows for thetorque limiting handle 114 to securely attach to the inserter instrument100. The torque limiting handle 114 may have a cylindrical canted spring198 embedded inside the attachment member 194. When the handle 114 isattached to the driver 116, the cylindrical canted spring 198 seatswithin the handle retaining saddle 194 such that when the inserterinstrument 100 is inverted, the torque limiting handle 114 will not falloff.

Instruments may be dropped in the operating room. If components are notsecured directly to each other, they may easily disassemble. Engagementfeatures like the spring tab 122, the driver engagement button 170,and/or the cylindrical canted spring 198 inside the torque limitinghandle 114 may help to ensure that the instruments stay affixed to eachother while the implant 10 is being inserted.

Turning now to FIGS. 50 and 51, a bone funnel assembly 200 is shown. Thebone funnel assembly 200 is configured to be used with the insertersleeve 110 and the threaded shaft 112 of the inserter instrument 100.The threaded shaft 112 is cannulated through the length of theinstrument. When the inserter sleeve 110 is attached to the implant 10,and no driver 116 is connected, the cannulation is one continuousdiameter through to the back of the implant 10. This allows for the bonefunnel assembly 200 to be placed down through the inserter instrument100 and align with the cannulation in the back of the implant 10. Bonegraft can then be placed through the funnel tube 204 to fill the insideof the implant 10, while the implant 10 is within the disc space.

The bone funnel assembly 200 includes a bone funnel 202 and a funneltube 204. The bone funnel 202 may thread onto the funnel tube 204 or beotherwise suitably affixed. The bone funnel assembly 200 is configuredto slide through the threaded shaft 112 and/or the guide shaft 120. Thebone funnel tube 204 is free to axially translate up and down thethreaded shaft 112 and/or the guide shaft 120. A graft pusher 206 is acylindrical shaft that slides down the funnel tube 204 and pushes thegraft material out the other end into the implant 10.

The geometric shape of the funnel 202 allows for ease of placement ofmaterial and the graft pusher 206 ensures ease of installation ofmaterial down the inserter 100. Thus, the insertion system provides forease of backfill to the implant 10 as well as ease of installation ofmaterial down the inserter 100.

It will be further understood that various changes in the details,materials, and arrangements of the parts which have been described andillustrated in order to explain the nature of this invention may be madeby those skilled in the art without departing from the scope of theinvention as expressed in the claims. One skilled in the art willappreciate that the embodiments discussed above are non-limiting. Itwill also be appreciated that one or more features of one embodiment maybe partially or fully incorporated into one or more other embodimentsdescribed herein.

What is claimed is:
 1. An implantable system comprising: an expandabledevice comprising a first endplate, a second endplate, a body positionedbetween the first endplate and the second endplate, and a drive screwand a lock positioned within the body, wherein rotation of the drivescrew is configured to increase or decrease a distance between the firstendplate and the second endplate, and the lock is configured to stoprotation to the drive screw, the drive screw having a head portion and ashaft, the head portion having a plurality of protrusions defining aplurality of notches therebetween, an annular ring, and acircumferential groove between the plurality of protrusions and theannular ring, the lock having a first ring and a second ring connectedto the first ring by a strut, wherein in a locked position, the secondring rests in the circumferential groove of the head portion, the strutis located in one of the notches, and the first ring of the lock restson a top face of the head portion.
 2. The implantable system of claim 1,wherein in an unlocked position, the second ring is translated out ofthe groove, and the strut is translated out of the notch, therebypermitting the drive screw to rotate by a driver.
 3. The implantablesystem of claim 1, wherein the first ring of the lock is a full ring. 4.The implantable system of claim 1, wherein the first ring includes anoff center through hole.
 5. The implantable system of claim 1, whereinthe second ring of the lock is a C-shaped spring ring.
 6. Theimplantable system of claim 1, wherein the plurality of protrusions andthe plurality of notches are located radially around a tip of the headportion.
 7. The implantable system of claim 1, wherein the plurality ofprotrusions include quadrilateral projections.
 8. The implantable systemof claim 1, wherein the expandable device further includes a retainingring configured to retain the lock and drive screw in the body of theexpandable device.
 9. The implantable system of claim 8, wherein theretaining ring has a generally C-shaped body.
 10. The implantable systemof claim 9, wherein the retaining ring includes a plurality of outerradial notches and a plurality of inner radial notches that allow thering to deflect without deforming.
 11. The implantable system of claim1, wherein the expandable device further includes a friction ringconfigured to reduce an expansion force and add friction to the drivescrew.
 12. The implantable system of claim 11, wherein the friction ringis an annular ring having an outer surface configured to contact thebody and an inner surface configured to contact the shaft of the drivescrew.
 13. An inserter instrument comprising: an inserter sleeveincluding an inserter body with a guide shaft extending from a proximalend to a distal end, and a handle at the proximal end, the guide shaftincluding a tubular member defining a channel therethrough, a firstplurality of splines defined within the channel at the proximal end; athreaded shaft positionable through the channel of the inserter sleeve,the threaded shaft includes a cannulated connector shaft, a slideincluding a second plurality of splines configured to engage with thefirst plurality of splines; and a driver positionable through thethreaded shaft, the driver includes a shaft with a linear cam configuredto engage the slider of the threaded shaft, wherein when the driver ispositioned through the threaded shaft and the linear cam engages theslider, the slider linearly translates towards the distal end, therebycausing the first and second plurality of splines to mate, and therebylocking an implant to the inserter instrument.
 14. The inserterinstrument of claim 13, wherein the threaded shaft includes anengagement member, and the linear cam includes one or more protrudingcam surfaces configured to mate with corresponding surfaces on theengagement member of the slider.
 15. The inserter instrument of claim13, wherein the distal end of the guide shaft terminates at opposed tabsconfigured to engage the implant.
 16. The inserter instrument of claim13, wherein the threaded shaft includes a threaded portion at its distaltip configured to engage the implant.
 17. A system for installing anexpandable implant, the system comprising: an expandable implantcomprising a first endplate, a second endplate, a body positionedbetween the first endplate and the second endplate, and a drive screwpositioned within the body, wherein rotation of the drive screw isconfigured to increase or decrease a distance between the first endplateand the second endplate; and an inserter instrument including aninserter sleeve, a threaded shaft positionable through the insertersleeve, and a driver positionable through the threaded shaft, theinserter sleeve including a guide shaft defining a channel therethrough,and a first plurality of splines defined within the channel, thethreaded shaft including a slide having a second plurality of splinesconfigured to engage with the first plurality of splines, the driverincluding a linear cam configured to engage the slider of the threadedshaft, wherein when the driver is positioned through the threaded shaftand the linear cam engages the slider, the slider linearly translatesforward, thereby causing the first and second plurality of splines tomate, and thereby locking the implant to the inserter instrument. 18.The system of claim 17, wherein the threaded shaft includes anengagement member, and the linear cam includes one or more protrudingcam surfaces configured to mate with corresponding surfaces on theengagement member of the slider.
 19. The system of claim 17, wherein adistal end of the guide shaft terminates at opposed tabs configured toengage the implant.
 20. The system of claim 17, wherein the threadedshaft includes a threaded portion at its distal tip configured to engagethe implant.